1. Field of the Invention
The present invention relates to a data carrier, in particular an identity card, and to methods for producing such a data carrier.
Specifically, the data carriers in question here are identity cards, e.g. check cards, credit cards, entitlement cards or calling cards and the like. Such identity cards have a standardized format and generally possess a multilayer structure. One side of the card shows general information applied e.g. by pressure or photographically, e.g. the name of a credit institution, an organization or the like, and possibly a security print (guilloche pattern) that is provided on the card surface or within the card. Furthermore, the user-related information, such as the name of the card owner, the customer number, the account number, the card number or the like, is provided.
2. Description of the Related Technology
In order to write on multilayer identity cards in color, German patent document no. 30 48 733 which corresponds to U.S. Pat. No. 4,523,777 the disclosure of which is expressly incorporated herein, proposes to provide different colored layer areas one on top of the other. The absorption behavior and vaporization points of the various color layers may be selected so that appropriate control of a laser beam intensity allows selective removal of color layers. The outermost color layer may be removed at lower laser beam intensities than the lower color layers.
The problem with these data carriers is that, due to tolerances of the layer thicknesses and small intervals between the vaporization or sublimation points, one often requires several radiation passes to obtain the complete removal of the various layers that is absolutely necessary for a high-contrast representation. With this writing method, several removal operations are thus necessary for each removed layer, which is an obstacle for large scale production of such data carriers. The color selection is also restricted by the fact that the color layers are coordinated with the laser beam intensity in terms of the absorption behavior of the particular color and the vaporization points of the various color layers.